Step 1

Preheat oven to 325 degrees F. Peel and thinly slice sweet potatoes on a mandoline; set aside. Heat heavy cream in a saucepan over medium heat, and add the cheese so it slowly melts into the cream. Mix in brown sugar, salt, and red pepper flakes; bring to a low simmer to incorporate all of the ingredients, 5–10 minutes. Butter the baking dish and evenly layer a quarter of the sweet potatoes along the bottom, then lightly sprinkle with salt.

Step 2

When the sauce is ready, pour a quarter of it over the sweet potatoes. Repeat the potato/sauce layering three more times until all of the ingredients are in the baking dish. Cover with foil and cook for 40 minutes. Remove foil and broil to brown the top, 5 minutes. Let sit for 10 minutes before serving.